Secondary batteries are rechargeable unlike primary batteries. Among such secondary batteries, a low capacity battery including a battery cell in the form of a pack may be used for small portable electronic devices such as cellular phones and camcorders, and a high capacity battery including dozens of battery cells connected to one another may be used as a motor-driving power source for electric scooters, hybrid vehicles, or electric vehicles.
Secondary batteries are manufactured in various shapes such as a cylindrical shape and a prismatic shape. A secondary battery is manufactured as follows: an electrode assembly formed by disposing an insulating separator between a positive electrode plate and a negative electrode plate is placed in a case together with electrolyte, and a cap plate is on the case. The electrode assembly is connected to positive and negative terminals which protrude from the cap plate and are exposed to the exterior of the electrode assembly.